THERE'S a new plant in town, and it can rip up your driveway, crack open your foundation and grow up to seven metres tall. Now, one expert is looking to the community to help take it on.
Japanese knotweed is an invasive species that thrives in temperate climates like the Lower Mainland's. While knotweed can be found across the Metro Vancouver area, the North Shore is ground zero for the tough, obnoxious plant, according to Jennifer Grenz, a coordinator with the Invasive Plant Council of Metro Vancouver.
"On the North Shore, where our crews have been working quite a bit on knotweed, we've seen it come through people's driveways, retaining walls, through roads," said Grenz. The plant can push through concrete "a couple metres thick," she said.
The problem has become so acute, it risks crossing the line from nuisance to serious financial liability, according to Richard Beard, owner of Green Admiral Nature Restoration, a company that often goes head-to-head with the plant.
In the U.K., which has its own knotweed problem, some banks are refusing to give a mortgage to homebuyers if the property is infested with the pest, he said.
"It's spreading at about 10 per cent a year (there)," said Beard. "Here it's spreading much quicker than that."
Tackling the menace is no easy chore, however. With roots that can grow three to four metres below the ground, it is notoriously tough to kill.
"The only way of getting rid of it permanently is with herbicide," said Beard. "The preferred method of doing it is with stem injection, so you go into each stem of the plant low down and you inoculate it directly. The herbicide stays within the plant and it doesn't affect anything else."
Grenz agreed that chemicals are the only viable approach.
"It's one of the most invasive plants in the world," she said. "It can't be cut; it can't be dug out. 0.2 grams of the plant results in a new one. . . . This is how it spreads so widely on roadsides; mowers go straight over top of it, and they don't know and quickly you turn one plant into 1 million plants."
Local municipalities are aware of the issue - knotweed may have been on the North Shore for as much as 50 years, according to the District of North Vancouver - but work crews haven't always been aware of the danger, said Ralph Nevill, the district's arboriculture and environment officer.
"In some cases our lawn crews have gone in with weed whackers, not realizing what it was. . . and what was once in one corner of an area soon is spread all over," he said.
Nevill warned residents to use garbage bags to dispose of it, and to keep it out of the compost.
"If you put it into the compost stream, that actually contaminates," he said. "We do not want to see it in your yard waste or in your table scraps waste."
Over the past few years, West Vancouver has been training staff to identify the weed in parks, and the municipality has been killing it with herbicide, said Corinne Ambor, manager of parks planning. But when it comes to homeowners, the community is still working on how best to deal with the issue.
"We have a pesticide bylaw in West Vancouver, and we're working on some information to get out to homeowners," said Ambor. Currently, the district tells residents not to cut down knotweed or dump it in another area.
"The No. 1 thing that people can do is not to dump their garden waste," said Ambor.
